TVA Uses Ellicott Dredge for Cleanup

April 9, 2009

Three months after a massive coal ash spill, the Tennessee Valley Authority (TVA) has begun dredging the ashen byproduct of coal-generated electricity from the Emory River using an Ellicott Series 370 "Dragon" dredge. Jacobs Engineering is the prime contractor for this first phase of the project.

The Ellicott 370 “Dragon” began sucking up ash from the river April 2, TVA officials said during a news briefing.

TVA's top environmental officer Anda Ray called the start of dredging a major milestone in the cleanup of one of the worst ash spills in the country's history - a recovery TVA estimates could cost more than $800m and take months if not years to complete.

Some 5.4 million cubic yards of ash breached earthen walls holding back a 60 ft-high landfill-like pile of ash at the Kingston plant three days before Christmas. More than a dozen homes were damaged or destroyed as the ash residue spilled out over a 300-acre area, covering a cove and flowing into the river, filling a navigation channel up to 27 ft deep.

Tim Hope, TVA's recovery project manager, said about 3 million cubic yards went into the Emory River. This first phase of dredging will recover a little more than half of that, he said. A layer of ash about 5 ft deep will be left on the bottom for dredging later.

The dredging will start slowly as TVA determines how to do it with the least disruption to residents and the environment. Dredge engines, pumps and compressors are being muffled. Floating water monitors look for signs the ash is being stirred up. "Turbidity curtains" are ready to drop into the water to prevent ash from flowing downstream. A half dozen air monitoring stations are checking air quality.

"Obviously, dredging the river is a proven activity. We know dredging will absolutely get it all out," Hope said. "The time frame associated with that and the amount of dredging, that is what the pilot project will determine."

TVA expects to know in about a month what is involved, and be able to award a dredging contract about a month later. That will likely pick up the pace. TVA is starting with daytime-only dredging, but wants to go 24-7 if it can.

"The big picture challenge for us right now is getting this ash out of the river," Hope said. "That is first and foremost for us right now ... getting it out in a timely manner."

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